Question

(0) Find the values of a and b, if (x - 1) and (x + 2) are both factors of (x3 + ax2 + bx - 6).​

Answer 1

Answer:

a= 4

b= 1

Step-by-step explanation:

x-1=0

x= 1

1³+a(1)²+b(1)-6 =0

1+a+b-6 =0

a+b= 5 (i)

x+2=0

x=-2

(-2)³+a(-2)²+b(-2)-6=0

-8+ 4a -2b -6=0

4a-2b = 14

2(2a-b)=14

2a-b=7 (ii)

By comparing (I) and equation (ii)

a+b=5

2a-b=7

3a= 12

a= 4

Putting value of a in (i)

4+ b = 5

b= 5-4

b= 1